Hi Guy's I had a crash today with my skywalker. It has never battered an eyelid at anything I have thrown at it and has flown many missions without a hiccup. Today I went for a fly at my usual haunt. I uploaded an auto flight with 4 waypoints (I have flown these waypoints before) and hand launched after waiting approximately 5 minutes for the GPS fix. I flew around for a minute or two whilst I positioned the goggles on my head and when they where on I flicked through stabilise to Auto. Once it went into Auto the engine reved up and the skywalker banked slightly to the left (to get on track) and pitched down violently, I tried to pull up but it did not respond at all, I went to Manual mode and by that time it was too late.
I did notice my airspeed went nuts but it was windy around 6 Knts variable. Also the HUD was not reflecting my pitched down angle, Also Ignore the Voltage on the screen, The Voltage has not been calibrated.
I have attached my .tlog, .log amd kmz file for everyone to look at. I have had a look but I can't decipher the logs. Also attached the FPV video as well as the Wing cam.
Another thing I noticed in the kmz file was showing I was flying in yellow stabilise but in actual fact I was in manual which should have been orange. the green in the middle of the yellow and blue reflects me going through Stabilise green to get to Auto black but the kmz shows me going into RTL which is blue. The OSD reflects me going into manual, taking off, flying then going through stabilise to get to auto, I never hit RTL ?
I hope it was something I have done because it was going so well and this was just unexpected.
Any info would be appreciated.
I will upload the Video's as soon as they get to youtube.
Here is the Video.
OK. I have wired the entire model back up and in stabilise, RTL, Auto, FBWA only the ailerons respond to the mag, the elevator in Stabilise,FBWA and RTL do not work at all but I can manipulate it via the remote, in AUTO and RTL the elevator locks half way down and I can not manipulate it.
Basically the elevator Mag is dead as far as I can tell. I was stupid and did not check it before takeoff but id did work yesterday.
Should I reset the board and re apply the firmware ? What could cause this. I am not one of those tinker's who plug and play with settings. I have only charged the battery's since the last time I flew.
Video from the wing cam
I used to have similiar issues with my Skywalker Condor 1880 hard bank and crash. Are you using APM2.5+ with power module and JP1 off. And powering your servos with external BEC and small separate battery instead from the esc?
Somehow for me the problem went away by itself. I don't experience this anymore. Whats different now is that im using APM2.5+ with the power module, JP1 off and my output rails(servos) are powered by external Castle 10A BEC at 6V . We supposed the power module helped a lot since we already was using separate BEC for the output when it was crashing. Also when we bought new APM 2.5+ it had the pink foam covering the baro which may have helped. Honestly now we don't know what really solved it, new hardware or new firmware. It my also be that our APM wasnt properly secured in our plane previously. So many hypothesis. But power module seems to be the more logical reson as previously the input voltage to the APM wasnt clean and constant at 5v and sometimes dropped way below 4.5V.
Whatother steps i take of course is to first balance the plane well, make sure its not too nose heavy or tail heavy. reduce your travel on the control surfaces to prevent stall especially during steep turns. Then i reduce the bank angle in Mission Planner.
So far after a couple of months no crashes. Hope you find out whats the real cause. Even though it doesn't crash on me anymore its kinda unnerving not really knowing the root cause.
Hi Adrian. I had exactly the same issue with my Bixler. I had a good takeoff in manual, switched to auto once the bird was up. She banked to the first waypoint, climbed out to 200m. Then on route to waypoint 2, did a sharp bank and nosedived from 200m to mother earth. My logs does not show anything about the last bank. It was only half way to waypoint 2.
I'm using an APM2.5 with GPS and telemetry. I've flown this configuration many times with a down facing camera. I was using 2.73 firmware, and like you, I don't fiddle much with settings. I checked the wiring and mounts before launch. All seemed fine. All I can think is that somehow the power in the setup went down. Yeah, so we learn. I'll split the power needs of my servos and APM from now on. Here are my log files as well....if it helps.
Hi K, I have the jumper off and a separate ubec supplying power to the APM. the VCC is 5.26 volts. The servos are also powered by a separate ubec. Current sensing is from a Rctimer C&V sensor. I have removed the Pink foam as the light was effecting the baro. I have used black foam and the light no longer effects the baro. Plane is balanced well slightly nose down at the correct C of G. I have over 25 flights on the plane and all has been well.
Just hope I can get to the root of the problem.
You should never poet your servos from the board. It does not supply enough current. The only thing I have done wrong is to update mission planner last night. I doubt that was the cause but I think it might be worth the dev team looking at.
I would like to better understand the APM logs so I decided to take a look at Adrian's. I'm not going to be able to solve this but could someone please tell me the difference between RELALT and ALT.
I have searched the Internet and can't find any reference to the two.
I Adrian. I've just looked at your video and kmz and they do not agree at all re. altutude. Your OSD frequently shows the wrong altitude especially towards the end. I can also see No GPS Lock flashing at least once. I'm thinking it's a GPS issue. I had the same thing, bad GPS lock sent my skywalker into the earth: https://www.youtube.com/watch?v=17GaSx7UbJY
I'll see if I can get time to check the tlog. Can you upload your parameters?
I dont have Parameters here they are on Ron's laptop. As soon as I can get to it (sometime tomorrow) I will post them for you. If the GPS fails shouldn't the Barometer take over ?. Its a bummer when you loose an A/C but I am happier we are getting on top of it not still wondering. Why would the GPS fail ? it is mounted up top of the Skywalker in front of the wing, No power wires near it, I am dumbfounded.
That video look eerily like mine. If you loose GPS you should still be able to fly shouldn't you. I could not even manipulate the controls.
Also My board locks half down elevator when in Auto mode now. and you can not manipulate the controll of the elevator in Auto anymore. My board is going back I am 100% certain it's a board issue but I have not ruled out the GPS theory either.
I just hope it does not happen again.
Here are your parameters. I extracted them from your onboard log.
It looks like your Pitch PID loop is way out of tune. the navigation controller is asking for more "up" elevator, and the pitch loop is responding with increasing output, but the output is way too low compared to your manual flight.
Did you change something about your setup before this flight? software version, parameters or something on your airframe, like CoG or connecting the elevator servo horn on a hole closer to the elevator/servo, resulting in less elevator authority?
Oh I almost forgot to mention, your aircraft was badly trimmed. When you put the elevator in neutral in your manual flight, the pitch and altitude start to drop fast. This wasn't helping.
I don't suspect a board issue or a GPS issue, because the GPS isn't used for altitude corrections (its set in your parameters)
If I would make a guess I would say the cause of your crash is a combination of a weak pitch controller action and a badly trimmed airframe. maybe it was nose heavy?
Best regards, Pieter
Great analysis Pieter.